In louverable rolling shutters, the individual shutter slats are articulated to pull and adjusting chain links so that the shutter slats can be pivoted from a rolling shutter position wherein the shutter slats fully shut off or cover the opening located therebehind, into a louvered position wherein light is able to penetrate between the thus-pivoted shutter slats. On account of the louver-adjusting device required for pivoting these shutter slats, special guide rails are needed in most cases for the installation of the rolling shutters. These guide rails must normally be wider than those of normal rolling shutters in order to be able to accommodate the louver device and/or parts thereof required for pivoting the shutter slats. As a consequence, retrofitting of normal rolling shutters already included in buildings with louverable rolling shutters is possible only with difficulties since the fixedly mounted frames and guide means must be replaced by those with larger dimensions. It is evident that it would be advantageous to design such louverable rolling shutters so that they can be installed in guide rails or guide profiles for normal rolling shutters without louvered design which are part of the original installation.
Louverable rolling shutters permitting such retrofitting of already present installations have been known (EP-A-0 189 091). In this arrangement, the louverable shutter slats are joined at their upper ends by pull chain links and at their lower ends by adjusting chain links. The pull chain links and the adjusting chain links are fashioned in this arrangement on one end in the manner of an eye and on the other end in the manner of a fork so that adjacent chain links can be composed in hinge-like manner. The shutter slats are received between respectively one pair of neighboring pull and adjusting chain links. This type of structure makes it inherently impossible to move the shutter slats into a closed tongue/groove position where the tongue provided in one shutter slat can be moved into a groove formed at the neighboring shutter slat for the production of a rolling shutter seal safe from breaking and entering.
Furthermore, the known louverable rolling shutter requires, besides the two chains of pull and adjusting chain links, another chain arranged along the edges at the shutter slats and made up of guide chain links guided in the fixedly installed guide profiles. The guide chain links are designed as slotted chain links and are joined hinge-like with one another by slotted bushings, i.e. bushings equipped with a longitudinal slot. The shutter slats are suspended by way of an articulated pin which latter is to be aligned axially with the slotted bushings of the guide chain links, which bushings must be designed correspondingly. In this arrangement, the slotted bushings must be designed, as connecting elements for the guide chain links, in such a way with regard to strength that they can withstand the stresses arising from the chain links disposed therebelow and from the shutter slats lying thereunder. Furthermore, the slotted bushings must be of such a structure that they can accommodate the hinge pins for the articulation of the shutter slats. Another function to be performed by these slotted bushings resides in that they must make it possible, during transition from the shuttered position into the louvered position, for the hinge pins to engage for the suspension of the shutter slats in the slots of the slotted chain links. Accordingly, the connection of the guide chain links must be designed in correspondence with the various functions; this is complicated and makes it difficult to accommodate guide chain links of such a design in already present guide rails for normal rolling shutters. Another drawback is to be seen in that the hinge sites for the articulation of the shutter slats to the guide chain links must be axially aligned with the axes of the slotted bushings, again resulting in structural limitations for the rolling shutter construction. Also, for transition from the shuttered position into the louvered position, corresponding stops must be provided at the shutter slats and at the guide chain links, as well as at a ventilating-position support to be specifically provided at the lowermost shutter slat. As seen in total, the conventional louverable rolling shutter is of a complicated structure, and operating failures cannot be excluded, either. Also, the coil circumference is comparatively large on account of the bulky adjusting and pull chain links attached to the front face as well as the rear face of the shutter slats. A further disadvantage resides in that the available see-through width for the zone that is louverable and/or available for looking therethrough is restricted on account of the three chains and the substantially strip-like design of the pull and adjusting chain links.
It is an object of the invention to provide a louverable rolling shutter which is of a simple and robust structure and also permits reliable louvered action. Furthermore, the rolling shutter is to be installable without difficulties in already present guide profiles for normal rolling shutters, and is to exhibit, upon winding, a coil diameter comparable to that of a normal rolling shutter.
This object has been attained in accordance with the invention by the features recited in the characterizing portion of claim 1, suitable further developments of the invention being characterized by the features-contained in the dependent claims.